Metalloidal material.



E. WEINTRAUB.

METALLOIDAL MATERIAL.

APPLICATION FILED MAY 28, 1912.

1 074 672, Patented Oct. 7, 1913.

INYENTUH .E'ZEE'HIEL J/I/ZI'JNTHAUB,

ire .srarn'r o FIFC EZECHIEL' -WEINTRAUB,1OFLYNNyMASSACHUSETTS,'ASSIGNOB. TO GENERAL ELECTRIC .COMPANY, ACORPGEATION GENEW' YORK.

METALLOIDAL MATERIAL.

1 Specification of Letters la-tent.

' Patented Oct. '7, 1913.

Original application filed October 27, 1909, Serial-No. 524,939. Dividedand. this application filed May 28, 1912. Serial No. 700,151.

To all whom it may concern:

Be it known that I, EZECHIEL WEINTRAUB, a citizen of theUnited States,residing at Lynn,-county of Essex, State of .Massachusetts, haveinvented certain new and useful Improvements in 'Metalloidal Material,(division of my former application, Serial No. 524,939, filed October27, 1909,) of which the following is a specification.

The present invention hasfor its object the production of elementalboron. This material may be used for a variety of purposes in thetechnical arts, as described and claimed in various copendingapplications.

The boron produced as herein described is not the material commonlydesignated as boron, in the technical literature. Moissan made what he,called boron by reduction of boric anhydrid with magnesium. He describedthe product asa brownish powder,

practically non-conductive for. electricity,

and vaporizable without fusion. Prior to my own lnvest gation of boronand itscompounds, this was the material generally recognized amongchemists as boron. I have, however, demonstrated that it is not pureboron at all. If the reaction is carried out as described byinvestigators preceding "Moissan, the product is magnesium borid,containing more or less magnesium; if the reaction is carried outaccording to Moissan,

:using an excessof boric anhydrid, a boron sub-oxid is formed mixed-withmore or less .magnesium borid.

I have found that pure boron is black, not brown, and that-it can be.fused into dense bodies having a conchoidal fracture, and a hardnessconsiderably reater than sapphire. Its melting pointis above 2000 (Landis not far from 2300 C. Its vapor tension is high. l/Vhile it has a highelectrical-resistance when cold, it possesses a negative temperaturecoeflicient of resistance of unprecedented magnitude, so that it acts asa fair conductor of electricity by the natural rise :in conductivity dueto the heating action of .the current. .I have found that at ordinary.room temperatures, the conductivity of pure ,boron doublesapproximately for every 17.

of temperatura In changing from room temperature to 400 C.,,:itsconductivity inv ,I. use pure, dry, hydrogem'and as a means creasesenormously, changing. according to high temperature my new materialcombineswith oxygen and is again converted into boric. anhydrid.

The present application, in so far as it claims a new material describedas elemental boron, is a continuation in part of my prior applications,Serial No. 316,007, filed May 9, 1906, and 346,253, filed December 4,1906.

,In both these applications this material is I treatment of themagnesium reduction product by a high voltage: are operating inhydrogen. In Patent No. 1,019,569, I have described and claimed the.method of making boron from a mixture of boric halid and hydrogen incontact with a heatedsurface.

I have described in detail in my parent application, Serial No. 524,939,the production ofhomogcneous fused boron by the reduction of boricchlorid in an electrical arc. Thedescription of this process is includedin the present divisional application as illustrative .of a method ofproducing pure elemental boron.

,In the drawings forming part. of this specification, Figure 1 -is anelevation,

somewhat diagrammatic, of one form of ap paratus for carrying out myinvention;

Fig. 2 is a fragmental view of a modified form of apparatus forintroducing the reaction mixture into the arc; and Flg. 3 is a detailview, being a cross-section of one of the-electrodes of Fig. 2.

,Boron chlorid is a colorless liquid, boiling at, about roomtemperature. It may be prepared by passing chlor n' over crude boron andredistil-ling the product over copper, which is quicker and moreeffective than. the usual shaking wlth mercury.

As a-reducing agent for the boron chlorld,

for efiecting the necessary temperature, I

use an electrical arc, maintained between suitable electrodes. But inaddition to this, the apparatus is so arranged that the arc blast drivesthe solid reduction product, namely, boron, out of the active zone anddeposits it on the. walls of the apparatus and on the electrodes; Thisis the only solid product present, the three other substances, boronchlorid, hydrogen and hydrochloric acid, being all gaseous, are allowedto pass on to an absorbing or condensing chamber. This reaction differsfrom any other reaction heretofore carried out in an electrical arc inhaving the desired reaction product in solid form, all the othersubstances present being gaseous. This is especially favorable, both forthe removal of the desired product, which is effected by the arc blastitself, and for the production of an absolutely pure product.

In the apparatus illustrated in Fig. 1, the liquid boron chlorid 1 iscontained in a glass or copper vessel 2, which is separated from theatmosphere by means of a small bulb 3 containing calcium chlorid for theabsorption of moisture. The vessel 2 is surrounded by a refrigeratingmaterial, such as the ice bath 4, to prevent the vaporization of theboron chlorid. The boron chlorid is introduced into the chamber 5 bymeans of a tube 6 having a stop cock 7 desired in any suitable manner,as I by means of an electrical coil 8. A small quantity of the liquidchlorid is introduced at intervals into the chamber 5, where it isvaporized and the vapor carried away with a stream of hydrogen enteringby the tube 9. The mixture of hydrogen and boron chlorid vapor leavingthe chamber 5 through an exit tube 10 passes into the two branch tubes11 and 12, which carry the mixture into the main arc chamber 13. Thischamber is made of glass or copper, or other suitable material, and isprovided with an inlet tube 141 for a supply of hydrogen, and with anoutlet tube 15, through which the unused hydrogen and boron chlorid, aswell as the hydrochloric acid forming as a byproduct of the reaction,are led to other parts of the apparatus. Within the arc chamber 13project the electrodes 16, 17, each consisting of copper tubing doubledon itself and cooled internally by a stream of water.

Forthe sake of simplicity, the water supply pipes have been merelyindicated in the drawing. Only one pair of electrodes is shown in thedrawing, though more can be used in a single arc chamber if desired. Analternating current are is preferably used, the current being suppliedas indicated from a transformer 18, the primary of which is in circuitwith suitable reactance 6011s 19, 20.

The chamber 5 may be heated if The mixture of hydrogen and boron chloridis introduced directly into the hot zone of the are by means of thenozzles 21, 22 of refractory material such as silica. The reduction ofthe chlorid by hydrogen is effected according to the followingtreatment: BCl +3H- 3HCl+B. The are blast throws the solid particles ofthe reducedv boron out of the hot zone against the walls of the arcchambers and against the electrodes themselves, and the hydrochloricacid gas is carried along with the hydrogen and any reduced boronchlorid toward the upper part of the arc chamber, where it is removed bythe tube 15. The boron deposited on the electrodes themselves is fusedby the heat of the arc, so that a part of the boron is yielded directlyas a homogeneous fused product. The are then runs between two boronelectrodes, the boron in some cases dropping off after having grown to acertain size, and another fused deposit of boron forming on theelectrode. In this connection, the choice of the electrode material isof great importance. It must have no affinity whatever for the reductionproduct, so as not to combine with the product depositing and melting onit; and, secondly, it must not electrically disintegrate and mix withthe powdered product. I have found that in the case of boron, copperfulfils these conditions perfectly; silver and gold alsoactsatisfactorily. If a second arc is arranged like the first and inseries with it, it will act on any reduced boron chlorid passing thefirst arc. The mixture of gases coming from the main arc chamber 13 andconsisting of hydrogen, hydrochloric acid gas and unreduced boronchlorid pass to a condenser 23, in which the boron chlorid not actedupon is again condensed to the liquid form and is caught in a suitablevessel 24. The condenser is of the usual form, and a discussion ofthesame in this connection is unnecessary. The mixture of hydrogen andhydrochloric acid gas passes from the condenser by means of a tube 25 toa chamber 26 containing sodium hydroxid, sodium amalgam, or othersubstance suitable for combining with the hydrochloric acid. Thepurified hydrogen passes out by a tube 27, and may be used over again.

Fig. 2 shows a modified form of apparatus in which the mixture of gasesto be acted upon is introduced by means of tubes 28, 29 passingcentrally through the electrodes. The electrodes proper consist ofcopperand are water-cooled, similar to the electrodes described in connectionwith Fig. 1, the circulation of cooling fluid being obtained byproviding the electrodes with a central partition extending nearly tothe end thereof and shown best in section, as 30 in Fig. 3. The coolingfluid passes in on one side of the partition and out on the other side.

What I claim as new, and desire to secure by Letters Patent of theUnited States,

1. The material herein described, the same being dense, black, hard,having a high melting point, being convertible by oxidation to boricanhydrid, being electrically conductive and having a very high negativetemperature resistance coefiicient, its conductivity approximatelydoubling for 17 C. rise in temperature above room temperature.

2. The material herein described, the same being black, having ahardness greater than sapphire, a conchoidal fracture, a melting pointabove 2000 C., of high electrical resistance when cold, having a highnegative temperature resistance coefiicient, and convertible byoxidation to boric anhydrid.

3. The material derived from a compound of boron, having a hardnessgreater than sapphire, a high negative temperature resistancecoefiicient, high electrical resistance when cold, being fusible, inertchemically with respect to copper and combining directly with chlorin toform a volatile colorless liquid.

4. The material herein described derived from a compound of boron,having a melting point above 2000 C., a hardness greater than sapphire,a high resistance when cold, a high negative temperature resistancecoeflicient and convertible by oxidation to boric anhydrid.

5. The material herein described the same being electrically conductiveand fusible, produced by interaction of boric chlorid and hydrogen athigh temperature, said material having great hardness, a conchoidalfracture, extreme purity and homogeneity- In Witness whereof, I havehereunto set my hand this th day of May, 1912.

EZECI-IIEL WEINTRAUB.

Witnesses:

JOHN A. MoMANUs, Jr., FRANK H. JOHNSON.

